The present invention relates generally to medical electronic devices, and specifically to implantable electrical devices for treatment of urge incontinence.
Urinary incontinence affects millions of people, causing discomfort and embarrassment sometimes to the point of social isolation. In the United States, it is estimated that 10-13 million patients seek medical care for incontinence each year.
Urge incontinence is a common type of urinary incontinence, in which a sudden, urgent need to pass urine causes involuntary urination before the patient can get to a toilet. Urge incontinence may be caused by damage to nerve pathways from the brain to the bladder or by psychosomatic factors, leading to involuntary bladder contraction. Urge and stress incontinence may also occur together, particularly in older women.
A large variety of products and treatment methods are available for personal and medical care of incontinence. Most patients suffering from mild to moderate incontinence use diapers or disposable absorbent pads. These products are not sufficiently absorbent to be effective in severe cases. They are uncomfortable to wear, and cause skin irritation, as well as unpleasant odors. Other non-surgical products for controlling incontinence include urethral inserts (or plugs), externally-worn adhesive patches, and drugs.
Exercise and behavioral training are also effective in some cases in rehabilitating pelvic muscles and thus reducing or resolving incontinence. Patients are taught to perform Kegel exercises to strengthen their pelvic muscles, which may be combined with electrical stimulation of the pelvic floor. Electromyographic biofeedback may also be provided to give the patients an indication as to the effectiveness of their muscular exertions. But retraining muscles is not possible or fully effective for most patients, particularly when there may be neurological damage or when other pathologies may be involved.
Medtronic Neurological, of Columbia Heights, Minn., produces a device known as Interstim for treatment of urge incontinence. Interstim uses an implantable pulse generator, which is surgically implanted in the lower abdomen and wired to nerves near the sacrum (the bone at the base of the spine) in a major surgical procedurexe2x80x94sometimes six hours under general anesthesia. Electrical impulses are then transmitted continuously to a sacral nerve that controls urinary voiding. The continuous electrical stimulation of the nerve has been found to reduce or eliminate urge incontinence in some patients. The batteries in the pulse generator must be replaced every 5-10 years. The strength and frequency of nerve stimulation are programmable, allowing the treatment to be tailored to the patient, and a hand-held programming device is available for this purpose.
U.S. Pat. No. 4,607,639, which is incorporated herein by reference, describes a method for controlling bladder function by nerve stimulation, typically of a sacral nerve. The anatomical location of at least one nerve controlling the muscles for the bladder and/or its sphincter is identified, and an electrode is placed on the nerve to selectively stimulate the nerve for continence and evacuation purposes. The electrode can be implanted in a patient either surgically or percutaneously and may be either removed after neurostimulation has achieved the desired result or may be left intact on the nerve for selective stimulation thereof. Further aspects and applications of these techniques are described in U.S. Pat. No. 4,739,764. U.S. Pat. No. 5,484,445 describes a system for anchoring a lead to the sacrum for purposes of long-term stimulation, typically for treatment of incontinence. Both of these patents are also incorporated herein by reference.
U.S. Pat. No. 3,628,538, which is incorporated herein by reference, describes apparatus for stimulating a muscle, using an electromyogram (EMG) signal sensed in the muscle. If the signal is greater than a threshold value, a stimulator circuit applies a voltage to electrodes adjacent to the muscle. The apparatus is said to be useful in overcoming incontinence.
Various types of electrodes have been proposed for applying electrical stimulation to pelvic muscles so as to prevent unwanted urine flow through the urethra. For example, U.S. Pat. No. 5,562,717 describes electrodes that are placed on the body surface, typically in the areas of the perineum and the sacrum, and are electrically actuated to control incontinence. U.S. Pat. No. 4,785,828 describes a vaginal plug having electrodes on an outer surface thereof. A pulse generator in the plug applies electrical pulses to the electrodes so as to constrict the pelvic muscles and prevent urine flow. U.S. Pat. No. 4,153,059 describes an intra-anal electrode, to which repetitive electrical pulses are applied in order to control urinary incontinence. U.S. Pat. No. 4,106,511 similarly describes an electrical stimulator in the form of a plug for insertion into the vagina or the anus. U.S. Pat. No. 3,866,613 describes a pessary ring having two electrodes thereon, which are energized to control incontinence. All of the above-mentioned patents are incorporated herein by reference.
U.S. Pat. No. 4,580,578, which is also incorporated herein by reference, describes a device for stimulating the sphincter muscles controlling the bladder. A supporting body is fitted into the patient""s vulva between the labia, so that two electrodes attached to the supporting body contact the epidermal surface on either side of the external urethral orifice. Electrical impulses are appiied to the electrodes to stimulate the region of the sphincter.
A book entitled Urinary Incontinence, edited by P. O""Donnell, Mosby Publishers, 1997, which is incorporated herein by reference, describes clinical aspects relating to the diagnosis and treatment of urinary incontinence.
It is an object of some aspects of the present invention to provide an improved device and method of treatment for incontinence, particularly urinary urge incontinence.
It is a further object of some aspects of the present invention to provide a device and method for enhancing function of muscles, particularly those associated with urine control.
In preferred embodiments of the present invention, a device for treatment of urinary incontinence comprises a control unit, one or more electrodes coupled to the control unit, and one or more optional sensors, also coupled to the control unit. Typically, but not necessarily, the device is used to treat urge incontinence. The electrode or electrodes are preferably implanted in the pelvic region of a patient so as to contact the one or more of the muscles or nerves that are used in regulating urine flow from the bladder. The control unit is preferably implanted under the skin of the abdomen or genital region, and receives signals from the electrodes and/or from the sensors. When the control unit determines that the signals are indicative of impending involuntary urine flow from the bladder, it applies a suitable electrical waveform to the electrode or electrodes, stimulating the contacted muscle or nerve to inhibit the urine flow.
In some preferred embodiments of the present invention, the electrodes are coupled to sense electromyogram (EMG) signals and/or to apply electrical stimulation to the detrusor muscle. The detrusor is responsible for bladder contraction and is believed to have a major role in causing, as well as relieving, urge incontinence. Although Medtronic""s Interstim nerve stimulator attempts to regulate detrusor contraction, it requires costly, major abdominal surgery for implantation. Preferred embodiments of the present invention offer a solution that is less invasive and lower in cost. Typically, in contrast to the Interstim stimulator, devices in accordance with preferred embodiments of the present invention actuate the electrodes to mediate urge incontinence only when physiological signals indicate that such mediation is needed. Numerous benefits are accrued, according to these embodiments, by actuating the electrodes only xe2x80x9con-demand,xe2x80x9d i.e., only when possible imminent incontinence is detected. For example, muscle fatigue and nerve irritationxe2x80x94both phenomena being associated with continuous excitationxe2x80x94are reduced or eliminated according to these embodiments. Additionally, power consumption is reduced, and battery life is thereby increased by limiting the electrical power output of the stimulator. Further additionally, safety may be increased, by decreasing the time during which possibly errant stimulation might cause a pelvic or non-peivic muscle to contract inappropriately. In other preferred embodiments of the present invention, however, the device may be configured to provide continuous stimulation.
Preferably, the electrodes are implanted so as to stimulate muscles of the pelvic floor. Alternatively or additionally, one or more of the electrodes may be implanted in or adjacent to the detrusor muscle or in a position suitable for stimulating a nerve, such as the sacral nerve, which controls detrusor function, as described in the above-mentioned U.S. Pat. No. 4,607,639, for example.
In some preferred embodiments of the present invention, the one or more electrodes comprise a single electrode, which both receives the EMG signals and applies the stimulation waveform. Alternatively, separate sensing and stimulation electrodes may be used.
In further preferred embodiments of the present invention, the sensors comprise one or more physiological sensors, such as pressure, force, motion or acceleration sensors, or an ultrasound transducer, which are preferably implanted on, in or in the vicinity of the bladder. The other sensors generate signals responsive to motion or to intravesical or abdominal pressure, or to urine volume in the bladder. These signals are thus indicative of possible incontinence. On the other hand, when the urine volume in the bladder is low, there will be no urine flow even when the abdominal pressure does increase. The control unit processes the signals from the other sensors and uses them to determine when the electrical stimulation should be applied.
Preferably, the control unit comprises a processor, which is programmed to distinguish between signals indicative of possible incontinence and other signals that do not warrant stimulation of the muscles. In particular, the processor is programmed to recognize signal patterns indicative of normal voiding, and does not stimulate the muscles when such patterns occur, so that the patient can pass urine normally. Preferably, in order to reduce consumption of electrical power, the control unit comprises a low-power, low-speed processor, which monitors the EMG signals continuously, and a high-speed processor, which turns on only when the low-speed portion detects an increase in EMG activity. The high-speed portion performs an accurate analysis of the signals to determine whether stimulation is actually warranted.
In a preferred embodiment of the present invention, the processor is programmable after implantation of the device, most preferably by means of a wireless communications link, so that the strength and shape of the stimulation waveform and the response of the device to the electromyographic and/or other physiological signals can be adjusted in response to the patient""s ciinical characteristics and experience with the device. The wireless link can also be used by the patient to turn the device on or off. Such methods of signal processing, programming and control, as well as other useful methods and apparatus, are described in a U.S. patent application entitled xe2x80x9cIncontinence Treatment Device,xe2x80x9d which is assigned to the assignee of the present patent application and is incorporated herein by reference.
Although preferred embodiments of the present invention are described with reference to treatment of urinary incontinence, particularly urge incontinence, it will be appreciated that the principles of the present invention may be applied as well to treat other types of incontinence, such as fecal incontinence, and to treat and enhance the function of other muscles in the body. Alternatively or additionally, principles of the present invention may be applied to treating constipation or pathological retention of urine, typically by stimulating some muscles to contract (e.g., muscles of the colon), while stimulating some parasympathetic nerves to induce relaxation of other muscles (e.g., the muscles of the anus). These applications of the invention may be particularly useful following spinal cord injury.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
a sensor, which generates a signal responsive to a physiological characteristic indicative of a likelihood of incontinence;
a control unit, which receives the signal from the sensor; and
at least one electrode, implanted in a patient and coupled to cause contraction of a pelvic muscle of the patient responsive to application of electrical energy to the electrode, to which electrode the control unit applies an electrical waveform responsive to the signal so as to inhibit the incontinence.
In a preferred embodiment, the control unit analyzes the sensor signal to determine a time of voiding, and applies the electrical waveform at a designated time interval subsequent to the time of voiding.
Preferably, the urinary incontinence includes urinary urge incontinence.
In a preferred embodiment, the control unit is implanted in a vicinity of the patient""s sacral spine.
Preferably, the electrode is implanted in the pelvic muscle of the patient. Further preferably, the pelvic muscle includes a pelvic floor muscle. Most preferably, the pelvic muscle includes the levator ani muscle or the urethral sphincter muscle, or, alternatively, the pelvic muscle is adjacent to the urethral sphincter muscle.
In a preferred embodiment, the electrode includes a single unipolar electrode or a pair of bipolar electrodes. Alternatively or additionally, the electrode includes a flexible intra-muscular electrode.
Preferably, the control unit receives data indicative of a fill level of the patient""s bladder and, responsive to the data, does not apply the electrical waveform when the fill level of the bladder is low, even when the signal generated by the sensor is indicative of involuntary urination.
In a preferred embodiment, the sensor includes a pressure sensor, an acceleration sensor, and/or an ultrasound transducer.
In a preferred embodiment, the electrode is electrically coupled to a nerve which innervates the pelvic muscle.
Preferably, the sensor includes a detecting electrode, and the signal includes an electromyographic (EMG) signal generated by the detecting electrode. In a preferred embodiment, the control unit applies the electrical waveform responsive to an average magnitude of the EMG signal, preferably responsive to the average magnitude of the EMG signal exceeding a designated threshold.
Preferably, the at least one electrode includes a detecting electrode, and the sensor includes the detecting electrode. In a preferred embodiment, the device includes a switch between the detecting electrode and an input of the control unit, which switch is opened when the electrical waveform is applied so as to prevent feedback from the detecting electrode to the input.
In a preferred embodiment, the electrode is electrically coupled to a nerve which innervates the pelvic muscle. Preferably, the nerve includes a sacral nerve.
Preferably, the control unit is implanted in the body of the patient and includes a rechargeable power source. In a preferred embodiment, the power source is recharged by inductive energy transfer, substantially without requiring electrical contact between the control unit and any object outside the patient""s body.
Further preferably, the control unit includes a processor, which analyzes the signal so as to determine when an involuntary urine flow is likely, whereupon the waveform is applied. In a preferred embodiment, the processor analyzes the signal at a sample rate substantially greater than 1000 Hz. Preferably, the processor""s analysis uses spectral analysis, and is performed on substantially non-rectified data.
Still further preferably, the processor is programmable to vary one or more parameters associated with the application of the waveform. In a preferred embodiment, the device includes a wireless receiver, which receives data for programming the processor from a programming unit outside the patient""s body.
Preferably, the processor includes a first processor, which analyzes the signal substantially continuously at a low data analysis rate, and a second processor, which is actuated by the first processor to analyze the signal at a high data analysis rate when the first processor determines that involuntary urine flow is likely to occur. Further preferably, the device includes a queue, in which the signal is stored before the second processor is actuated, and from which queue the signal received by the control unit prior to actuation of the second processor is passed to the second processor for analysis.
Preferably, the processor distinguishes between a signal indicative of an involuntary urine flow and a signal indicative of voluntary voiding by the patient. In a preferred embodiment, the processor distinguishes between the signal indicative of involuntary urine flow and the signal indicative of voluntary voiding by the patient responsive to a rate of change of the signal generated by the sensor.
In a preferred embodiment, the processor gathers information regarding the signal over an extended period and analyzes the information to find a pattern characteristic of the patient, for use in determining when an involuntary urine flow is likely. The pattern may include a time-varying threshold to which a level of the signal is compared.
There is further provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence in a patient, including:
a sensor, which is coupled to generate a signal responsive to a fill level of the patient""s bladder; and
a control unit, which receives and analyzes the signal so as to determine a fill level of the bladder and, responsive to the determination, applies electrical stimulation to cause the contraction of a pelvic muscle of the patient, so as to inhibit the urinary incontinence when the fill level of the bladder is above a threshold level.
Preferably, the incontinence includes urge incontinence. Alternatively or additionally, the incontinence includes stress incontinence.
Preferably, the device includes an electrode, which is placed in electrical contact with a nerve which innervates the pelvic muscle, and the stimulation includes an electrical waveform applied to the electrode so as to stimulate the nerve to cause the muscle to contract, thereby inhibiting the incontinence. Alternatively or additionally, the device includes an electrode, which is placed in electrical contact with the pelvic muscle of the patient, wherein the stimulation includes an electrical waveform applied to the electrode so as to stimulate the muscle to contract, thereby inhibiting the incontinence.
Preferably, the control unit receives a signal indicative of a likelihood of involuntary urination and applies the stimulation to the pelvic muscle responsive to the likelihood except when the fill level of the bladder is below the threshold level. In a preferred embodiment, the sensor includes an electrode, which is placed in electrical contact with the pelvic muscle of the patient to receive an electromyogram signal therefrom indicative of the likelihood of involuntary urination and of the fill level.
There is still further provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
at least one electrode, which is coupled to a pelvic muscle of a patient; and
a control unit, which receives electromyogram signals from the electrode indicative of possible imminent incontinence, and which determines a threshold signal level that varies over time responsive to a condition of the patient, and which, responsive to a transient increase in the electromyogram signal above the threshold level, applies an electrical waveform to stimulate the muscle to contract, so as to inhibit the incontinence.
Preferably, the control unit applies the waveform to the electrode.
In a preferred embodiment, the device includes a second electrode, coupled to a nerve which innervates the pelvic muscle, and the control unit applies the waveform to the second electrode to cause contraction of the muscle.
Preferably, the threshold signal level varies over time responsive to temporal variation of a mean value of the electromyogram signal. Alternatively or additionally, the threshold signal level increases responsive to time elapsed since the patient last passed urine. Further alternatively or additionally, the threshold signal level increases responsive to an increase in a fill level of the patient""s bladder.
There is yet further provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
at least one electrode, which is placed in electrical contact with a pelvic muscle of a patient; and
a control unit, which receives electromyogram signals from the electrode and, responsive to a rate of change of the signals indicative of possible imminent incontinence, applies an electrical waveform which stimulates the muscle to contract, so as to inhibit the incontinence.
Preferably, when the rate of change is below a threshold rate, the control unit withholds the waveform, so as to allow voluntary voiding.
There is also provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
at least one electrode, which is placed in electrical contact with a pelvic muscle of a patient; and
a control unit, which receives signals indicative of impending urine flow, and distinguishes signals indicative of possible imminent incontinence from signals indicative of voluntary voiding by the patient, and responsive thereto applies an electrical waveform to the electrode which stimulates the muscle to contract, so as to inhibit incontinence.
In a preferred embodiment, the control unit distinguishes between the signals indicative of incontinence and the signals indicative of voluntary voiding by the patient responsive to a rate of change of the received signals.
Preferably, the control unit distinguishes between the signals indicative of incontinence and the signals indicative of voluntary voiding, substantially without application of an input to the control unit from outside the patient""s body.
In a preferred embodiment, the control unit gathers information regarding the signals over an extended period and analyzes the information to find a pattern characteristic of the patient, for use in determining when incontinence is likely. Preferably, the pattern includes a time-varying threshold to which a level of the signals is compared.
There is additionally provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
at least one electrode, coupled to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode; and
a control unit, which receives at a sample rate substantially greater than 1000 Hz signals indicative of possible imminent incontinence, analyzes the signals so as to determine when the incontinence is likely, and, responsive thereto, applies an electrical waveform to the electrode which causes the muscle to contract, so as to inhibit the incontinence.
There is still additionally provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary incontinence, including:
at least one electrode, coupled to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
a first processor, which receives signals indicative of a likelihood of imminent incontinence and analyzes the signals substantially continuously at a low data analysis rate; and
a second processor, which, responsive to a determination by the first processor that incontinence is imminent, is actuated by the first processor to analyze the signals at a high data analysis rate and, responsive to the analysis at the high data rate, applies an electrical waveform to the electrode which stimulates the muscle to contract, so as to inhibit the incontinence.
Preferably, the device includes a queue, in which the signals are stored before the second processor is actuated, and from which queue signals received by the first processor prior to actuation of the second processor are passed to the second processor for analysis.
There is yet additionally provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary incontinence, including:
coupling an electrode to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
receiving a signal from the patient""s body indicative of impending urine flow;
analyzing the received signal to distinguish between a signal indicating that incontinence is likely and another signal indicative of voluntary voiding; and
responsive to the analysis, applying an electrical waveform to the electrode, which stimulates the muscle to contract so as to inhibit incontinence.
In a preferred embodiment, distinguishing between the signals includes gathering information regarding the received signal over an extended period and analyzing the information to detect a pattern characteristic of the patient, for use in determining when incontinence is likely. In a preferred embodiment, the pattern includes a time-varying threshold to which a level of the received signal is compared.
There is further provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary incontinence, including:
coupling an electrode to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
receiving at a sample rate substantially greater than 1000 Hz signals indicative of imminent urination;
analyzing the signals so as to determine when incontinence is likely; and
responsive to the analysis, applying an electrical waveform to the electrode, which stimulates the muscle to contract so as to inhibit incontinence.
Preferably, analyzing includes distinguishing between a signal indicating that involuntary urine flow is likely and another signal indicative of voluntary voiding.
There is still further provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary stress incontinence of a patient, including:
implanting an electrode so as to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
receiving a signal from the patient""s body indicative of imminent incontinence; and
responsive to the signal, applying an electrical waveform to the electrode, which stimulates the muscle to contract so as to inhibit incontinence.
In a preferred embodiment, implanting the electrode includes implanting the electrode in the pelvic muscle. Alternatively or additionally, implanting the electrode includes implanting an electrode in proximity to the urethral sphincter muscle.
Preferably, applying the waveform includes varying a parameter of the waveform selected from the group consisting of: amplitude, frequency, duration, wave shape and duty cycle. Alternatively or additionally, applying the waveform includes applying a pulse burst. Further alternatively or additionally, applying the waveform includes applying a waveform to the electrode in a unipolar mode. Still further alternatively or additionally, implanting the electrode includes placing at least two electrodes in electrical contact with the muscle, and applying the waveform includes applying a waveform between the electrodes in a bipolar mode.
In a preferred embodiment, receiving the signal includes receiving a signal indicative of pressure on the patient""s bladder and/or indicative of motion of the patient""s bladder.
Preferably, receiving the signal includes receiving an electromyographic (EMG) signal.
Further preferably, the method includes determining a time of voiding, wherein applying the electrical waveform includes applying the waveform at a designated time interval subsequent to the time of voiding.
In a preferred embodiment, implanting the electrode includes coupling the electrode to a nerve which innervates the pelvic muscle. Preferably, the nerve includes a sacral nerve.
Preferably, the method includes receiving a signal indicative of a fill level of the patient""s bladder, wherein applying the electrical waveform includes applying a waveform responsive to the fill level. Further preferably, applying the waveform responsive to the fill level includes withholding application to the waveform when the fill level is low, notwithstanding the signal received indicative of abdominal stress.
There is still further provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary incontinence, including:
receiving a signal indicative of a fill level of a patient""s bladder; and
applying stimulation to a pelvic muscle of the patient when the fill level of the bladder is above a threshold level, so as to inhibit incontinence.
Preferably, applying the stimulation includes applying an electrical waveform to an electrode in contact with the pelvic muscle, thereby stimulating the muscle to contract and inhibiting incontinence.
In a preferred embodiment, the method includes receiving a further signal indicative of a likelihood of imminent incontinence, wherein applying the stimulation includes applying stimulation responsive to the likelihood except when the fill level of the bladder is below the threshold level. Preferably, receiving the signal includes receiving an electromyogram signal from an electrode in contact with the pelvic muscle, wherein the signal is indicative of the likelihood of imminent incontinence and of the fill level.
There is yet further provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary incontinence, including:
coupling an electrode to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
receiving electromyogram signals from the electrode indicative of a likelihood of imminent incontinence;
determining a threshold level of the signals that varies over time responsive to a condition of the patient; and
responsive to a transient increase in the signals above the threshold level, applying an electrical waveform to the electrode which stimulates the muscle to contract, so as to inhibit incontinence.
In a preferred embodiment, determining the threshold level includes determining a level that varies over time responsive to temporal variation of a mean value of the electromyogram signals. Alternatively or additionally, determining the threshold level includes increasing the threshold level responsive to time elapsed since the patient last passed urine. Further alternatively or additionally, determining the threshold level includes increasing the threshold level responsive to an increase in a fill level of the patient""s bladder.
There is also provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary incontinence, including:
coupling an electrode to cause contraction of a pelvic muscle of a patient responsive to application of electrical energy to the electrode;
receiving electromyogram signals from the electrode indicative of a likelihood of imminent incontinence;
determining a rate of change of the signals; and
responsive to the rate of change, applying an electrical waveform to the electrode which stimulates the muscle to contract, so as to inhibit incontinence.
Preferably, applying the waveform includes applying a waveform when the rate of change is above a threshold rate, and includes withholding the waveform when the rate of change is below the threshold rate, so as to allow voluntary voiding.